ABSTRACT The purpose of the University of Pittsburgh Low Back Pain: Biological, Biomechanical, Behavioral Phenotypes (LB3P) Mechanistic Research Center is to perform in-depth phenotyping of patients with chronic low back pain (CLBP), using a multi-modal approach, to characterize patients and provide insight into the phenotypes associated with experience of CLBP to direct targeted and improved treatments. This new center will uniquely address the critical challenge facing care for patients with CLBP, which is the rising costs of care related to failed treatments, and resultant loss of quality of life and function with increasing reliance on opioid use resulting from our inability to properly select patients for properly targeted treatments with a high likelihood of success. The LB3P MRC will be formed of three Research Cores, which will be primarily responsible for data collection and analysis of the three key contributors to CLBP (Biological, Biomechanical, and Behavioral); three support cores primarily responsible for data organization, processing, storage and dissemination, including interactions with the BACPAC (Administrative, Clinical, and Informatics); and one Research Project (deep phenotyping of CLBP patient characteristics and response to treatments), serving to leverage all of the services and products of the individual cores into the development of a unique clinical set of phenotypes associated with response to treatment to guide properly targeted, individualized future care models for CLBP. This approach will leverage and integrate distinctive resources at the University of Pittsburgh laboratories to deliver quantified biomechanical, biological, and behavioral characteristics, functional assessments and patient-reported outcomes, coupled with advanced data analytics using a novel Network Phenotyping Strategy (NPS). A comprehensive and integrated biopsychosocial approach will be employed, which is necessary to improve treatment for this complex and multi-dimensional condition. It is critical that the interaction of individual variables is maintained in any phenotyping strategy, since in the syndrome of CLBP there is significant interaction of each contributor, and this is an important strength of the proposed approach. The formation of this center will build upon existing strengths within the University of Pittsburgh research community and focus efforts around the critical challenge of CLBP, and the collaborative approach will serve as an important resource for the BACPAC community. The LB3P MRC will coordinate the interdisciplinary expertise of clinicians and researchers to study the contributors and predictors of CLBP, and to propose a culminating research project that promises to translate the findings to clinical utilization and change the paradigm of care for CLBP. The proposed approach, by eliminating isolated and disconnected approaches to treatment, and instead focusing on personalized patient- centric approaches, will yield improved outcomes and patient satisfaction. In addition, the robust environment, including an academic medical center with an integrated care delivery and finance system, will ensure rapid and efficient translation of the results into novel care models for CLBP patients.